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Friday evening when I was at a red light my 2004 bmw 325i started to idle very roughly and run below 1,000 RPM's.

I took it to AutoZone Saturday morning and had them run a test on it to see what codes it pulled, codes were as followed:
P0171
P0174
P0706
P2237
P2240

The guy at AutoZone said it was most likely my mass air flow sensor causing it to idle so hard. I did a little research on this forum as well as another and a majority of the cars who pulled the same codes either had to replace the MAS or had a problem with vacuum.

I have replaced the MAS so I know it's not that, checked out the vacuum lines and also checked out the DISA. I decided to bring it up to another auto part place and have them run the tests. The same codes pulled. This guy suggested that due to code "P0174" being pulled that it's most likely a problem with an ignition coil or spark plug. On my way home from that auto part store my car put itself into "limp transmission mode". The only odd thing it does in that mode is when I slow down to about 15 mph, it feels as if I'm pumping the brakes twice.

Anyone have any input as to what this could be? Could a bad ignition coil or spark plug for that matter cause the car to enter limp mode?

Before I bring it to the dealership tomorrow I wanted to see if I could fix the problem myself.
hellobmx325i is offline Reply With Quote

If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replace the air filter and clean the MAF.

2237 and 2240 relate to oxygen sensors but these codes will trip when the conditions are too lean, again from a leak somewhere in the intake system.
Intake tubing going down to ICV and TB, CVV hoses or the intake manifold itself could be leaking. I think all four of these codes point to a leak.

P0706 is why it went into limp mode: "Transmission Range Sensor Circuit Range/Performance"---The park/neutral position switch includes a transmission range switch. The transmission range switch detects the selector lever position when the shift lever is in the N or P shift position and sends a signal to the Transmission Control Module. Could be Open or short / failed park/neutral position switch?